1. Field of the Invention
The present invention relates to a squeegee roller cleaning apparatus for a liquid electrophotographic printer and, more particularly, to a squeegee roller cleaning apparatus for a liquid electrophotographic printer having a blade with an improved structure and shape for removing developer remaining between a squeegee roller and a photoreceptor web.
2. Description of the Related Art
FIG. 1 shows the structure of a conventional liquid electrophotographic printer. Referring to FIG. 1, a development unit of a conventional liquid electrophotographic printer includes a photoreceptor web 10 circulating by being supported by a plurality of rollers 11, a tray 12 installed under the photoreceptor web 10 for collecting developer remaining after being used for development, a development roller 14 supported by a development frame (not shown) and moving up and down by an elevating means (not shown), a manifold 20 for injecting developer into a gap G (hereinafter, referred to as a development gap) formed between the development roller 14 and the photoreceptor web 10, a development tank 13 for collecting and holding the developer injected into the development gap G, a development roller cleaning apparatus for removing developer adhering to the outer circumferential surface of the development roller 14, and a developer removing means for removing developer remaining on the photoreceptor web 10 after being used for the development.
The development roller cleaning apparatus consists of a brush roller 18 for cleaning developer adhering to the development roller 14, by being supported by the development tank 13 and rotating in contact with the development roller 14, and a development blade 22 having one end in contact with the outer circumference of the development roller 14 and the other end assembled to the body of the manifold 20, for removing developer remaining between the brush roller 18 and the development roller 14 and transferred to the surface of the development roller 14. Reference numeral 24 denotes a packing member for discharging developer in the development tank 13 into the tray 12 and reference numeral 26 denotes a stopper for limiting the movement of the packing member 24.
The developer removing means consists of a squeegee roller 15 installed adjacent to the development roller 14 for pressing and removing developer adhering to the photoreceptor web 10, an air injection nozzle 16 for removing developer by injecting air into a portion where the squeegee roller 15 contacts the photoreceptor web 10, a squeegee blade 17 for removing developer flowing down along the outer circumference of the squeegee roller 15 while being in contact with the surface of the squeegee roller 15.
During development, the development roller 14 ascends toward the photoreceptor web 10 to maintain the development gap G in the tray 12. As the development roller 14 moves, the development tank 13 and the manifold 20 are moved upward together. The manifold 20 injects developer into the development gap G and, as the development roller 14 rotates, an area for an electrostatic latent image formed on the surface of the photoreceptor web 10 is developed. Developer carrier adhering to the area for an electrostatic latent image on the photoreceptor web 10 is removed by the developer removing means.
In other words, the squeegee roller 15 is in contact with the photoreceptor web 10 and passively rotated thereby in a direction in which the photoreceptor web 10 travels. In doing so, the squeegee roller 15 presses the developer adhering to the electrostatic latent image area so that toner becomes filmy and most of the carrier other than the filmy toner is removed. Here, the air injection nozzle 16 injects air toward the squeegee roller 15. That is, the carrier squeezed by the squeegee roller 15 flowing along a contact line between the squeegee roller 15 and the photoreceptor web 10 meets the air injected by the air injection nozzle 16 to scatter and fall downward. Here, the blade 17 maintains a state of being separated a predetermined distance from the outer circumferential surface of the squeegee roller 15.
As shown in FIG. 2, after the development mode is terminated, the development roller 14 descends in the tray 12. As the development roller 14 moves down, the packing member 24 contacting the stopper 26 relatively ascends to open a lower portion of the development tank 13. Thus, the developer in the development tank 13 is discharged into the tray 12.
However, a drip-line is generated as developer continues to remain between the photoreceptor web 10 and the squeegee roller 15. The drip-line is generated when developer gathers at a portion where the squeegee roller 15 and the photoreceptor web 10 closely contact each other during development. To remove the drip-line developer, in a state in which the operating speed of the photoreceptor web 10 is reduced, a pressing force of the squeegee roller 15 which presses the photoreceptor web 10 is slightly reduced. Then, by driving the squeegee roller 15 to rotate in the reverse direction to the direction in which the photoreceptor web 10 travels, the drip-line developer is removed due to the rotation of the squeegee roller 15. The removed developer flows down along the squeegee roller 15 and falls into the tray 12 by being wiped by the blade 17. The developer falling into the tray 12 is collected on the bottom surface of the tray 12 and supplied to a circulation tank (not shown).
In the developer removing means of the development unit having the above structure, the squeegee blade 17 must satisfy the conditions as follows.
First, the developer falls downward without a hold up volume phenomenon occurring when the developer is maintained at a contact point between the leading edge of the blade and the squeegee roller, so that developer does not adhere to the surface of the blade.
Second, the developer must be completely removed so that the developer does not remain on the surface of the squeegee roller.
Third, the blade must not be flipped over to the reverse due to a rotational moment by the rotation of the squeegee roller. That is, as the blade is deformed by the friction with the squeegee roller, the leading edge of the blade must not be lifted, either partially or entirely, from the surface of the squeegee roller.